I. Field
The present disclosure relates generally to imaging rendering, and more specifically to techniques for automatically extracting print image matching (PIM) parameters that can be automatically adjusted to produce a better looking (visually enhanced) image.
II. Background
Referring to FIGS. 1A and 1B, the gamut curve for a typical color gamut is denoted as 2 and has a generally horseshoe shape. The horseshoe shaped gamut curve 2 represents the entire range of possible colors. Overlaid in the horseshoe shaped gamut curve 2 is the gamut curve denoted as 4 for an image taken by a digital still camera image. The gamut curve denoted as 6A is for a standard red, green blue (sRGB) display device, such as a CRT or other typical computer monitor, and has a generally triangular shape. The corners of the triangle represent the primary colors red (R), green (G) and blue (B) of the gamut. In FIG. 1B, in lieu of the gamut curve 6A, a gamut curve denoted as 6B is overlaid which is the gamut curve for an EPSON® 6-color inkjet printer.
As can be readily seen, the color gamut is device-dependent. A digital still camera device may be able to capture more colors than what a sRGB display device can render. Moreover, a multi-ink printing device has a wider color gamut than the sRGB display.
Print Image Matching (hereinafter, PIM) is technology introduced by EPSON® to allow a camera/user to specify settings that are later used by the printer to process an image at print time. The PIM technology enables conveying the image “as captured” to the printer along with control information used to instruct the printer to perform certain operations. The PIM technology creates information outside of the visible color space of a sRGB display that could be used to print on a printer's wider color space. The PIM technology also provides active control of image print quality by a camera's manufacturer or user.
For example, PIM technology allows a camera's subsystem to correct for light/color imbalances occurring at the time of taking a picture without processing the image; the parameters for processing the image are included in the EXIF header (PIM tag) and are later used by the printer to apply picture specific processing. The camera user can also potentially specify types of pictures (i.e., portrait, landscape scenery, etc.) which can be interpreted by the camera subsystem information PIM parameters. The PIM technology supports multiple parameters with often overlapping scope.
An image with the PIM correction ON is corrected for light/color imbalances when rendered on or by a display device. The same image with the PIM correction OFF may appear lighter or darker due to light/color imbalances. Specifically, the PIM parameters are used to make the image more balanced. For example if the image is too bright, the PIM parameters can make the image darker. However, if the image is too dark, the PIM parameters can make the image brighter.
However, the ease of use of PIM parameters has generally been unacceptable.